Why are there dark shadows on model in edit view?
Your normals appear to be flipped. That dark shading is the back side of the face, also known as the Backfacing.

To check if this is the problem, open the N panel in edit mode, go to the Mesh Display Tab, and check the box for Display Face Normals. This will make a line from the center of the face that points in the direction the normal is facing.

If this does turn out to be the problem, you can recalculate or flip the normals of a selected face by using the Recalculate or Flip Directions command under the Shading/UVs tab in the T panel.